<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <script>
        var a = 0;
        b = 0;

        function A(a) {
            // var  a = 1;

             A = function (b) {
                //  b = 2 
                // b = ++b // 3 
                // b = 3
                console.log("ok")
                console.log((b + ++b));
            }
            console.log((a++), 'ok');
        }
        // console.log(A(1)); 
        // console.lof(A(2));
        A(1);  // 1 'ok'
        A(2);  // ok 5
        A(3); // ok 7    
    </script>
</body>

</html>